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3.2.2 Supports:
Check the piping supports where the rubber expansion joint will be installed. Piping to and from
the location of installation for the expansion joint must be properly supported and guided to
ensure that the weight of the piping is not transferred to the expansion joint.
3.3 Pipe Alignment
Inspect the system for proper alignment as stated in the procedures listed below for axial, lateral, angular
and torsional alignment. Piping misalignment in the system should not exceed a maximum of ±1/8” per the
Fluid Sealing Association (FSA). If the maximum allowable misalignment is exceeded, the piping should
be corrected before installation of the expansion joint. The piping must be prepared to receive the rubber
expansion joint, never the contrary, as this would result in compressing, extending, laterally deflecting or
angularly bending the expansion joint until it fits into the available clearance for installation. This will result
in additional movements for the expansion joint, thereby decreasing its movement capabilities during
operation and lead to a possible failure.
3.3.1Axial Misalignment
To measure for axial misalignment, measure the
perpendicular distance from the inside of one
mating flange to the inside of the other, the area in
which the expansion joint is to be installed. This
measured dimension should correspond to the
ordered expansion joint’s face-to-face or overall
length dimension otherwise an axial misalignment
is indicated.
3.3.2 Lateral Misalignment
To measure for lateral misalignment, place a
level on the outside edge of the mating flanges
and measure the distance across. Repeat the
measurement at least 3 times to obtain a total of
4 measurements evenly distributed around the
circumference of the mating flanges (6-8 total
measurements for large ID expansion joints). Any
variation in the measured dimensions and an
inconsistency in the level, indicates a lateral
misalignment.
3.3.3Angular Misalignment
To measure for angular misalignment between
mating flanges, the distance from one mating flange
to the other will need to me measured. Measure the
perpendicular distance from the inside of one
mating flange to the inside surface of the other
mating flange. Take several of these measurements
in various positions around the mating flanges. Any
variation in the measured dimensions indicates that
the mating flanges are not parallel and are angularly
misaligned.
Figure 4: Axial Misalignment
LATERAL OFFSETLATERAL OFFSET
Figure 5: Lateral Misalignment
ANGULAR OFFSET
Figure 6: Angular Misalignment
